How to load UDIM images which sequence number does not start with "1001"?
So far I have come up with three solutions, but none of which are sufficient.

Assign all materials to tile '1001'. It's better to assign to a mesh that is hard to find.
Create an empty image file for each texture set that does not have a '1001' file.

e.g.: If 'eyes_BaseColor_1002.png' exists, but 'eyes_BaseColor_1001.png' does not, you should create 'eyes_BaseColor_1001.png' (2*2 px blank image).
If you use this method frequently, it's better to write a program for it.


Create individual materials only for texture that were not recognized as UDIM.

(I know, this is the worst solution)